Pixels of an image sensor are arranged, e.g., in a Bayer array. In such an image sensor, G pixels (green pixels) include Gr pixels located in rows of R pixels (red pixels) and Gb pixels located in rows of B pixels (blue pixels). The Gr pixels and the Gb pixels are preferably equal in terms of sensitivity. However, a sensitivity difference occurs due to a pixel arrays, non-uniformity of color filter films, differences of readout characteristics in a pixel arrays or the like. Accordingly, the sensitivity difference needs to be corrected.